The present invention relates to an image recording apparatus and more particularly, to an image recording apparatus having an improved drive control of a cooling fan for least quiet cooling operation.
In a copying machine of electrostatic recording method, its image recording section is constructed as shown in FIG. 3. A charging electrode 1 charges a high voltage onto a surface of a conductive sensitizing body (photoreceptor) 2. If an image light 3 carrying image information coming in while the sensitizing body 2 is revolving in the direction of arrow a, the charge of the sensitizing body 2 changes. An electrostatic latent image, then, is formed there. The latent image is developed by a developing unit 4 to a toner image. On the other hand, a copying sheet 8 that has be fed to a registration roller 7 from a paper feeder section 5 by a sheet feeding roller 6, is re-fed from the registration roller 7 to a copying electrode 9 at a time when the copying sheet 8 matches with a beginning of the toner image. The toner image, then, can be copied onto the copying sheet 8. The copying is made in a way that a potential higher than that of the sensitizing body 2 is applied to the copying electrode 9. The copying sheet 8 on which the toner image has been copied is separated from the sensitizing body 2 by a separation electrode 10, and is carried to a thermal setting unit (fixing unit) 11. The thermal setting unit 11 has a heating roller 11A comprising an aluminum cylinder having a heater therein, have a pressure roller comprising a rubber roller inside there.
The image recording apparatus having such an thermal setting unit 11 incorporated therein produces some heat therein, which causes some difficulties. It therefore has a cooling fan 12 for air exhaustion.
In the conventional technique, the cooling fan 12 is controlled to operate at cyclic timings as shown in FIG. 6. In the cyclic operation, with power being on, a low-speed exhaustion, or idling, starts. When copying is started thereafter, it is switched over to a high-speed exhaustion. With end of copying, the operation is reset to the low-speed exhaustion again.
In the conventional operation, this is always set in the high-speed exhaustion state with start of copying. This involves a loud operation sound, which prevents quiet office works.